Vlasov model for the impedance of a rod-pinch diode

Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference (IEEE Cat. No.03CH37472) Pub Date : 2003-06-15 DOI:10.1109/PPC.2003.1277977

P. Ottinger, J. Schumer, S. Strasburg, S. Swanekamp, B. Oliver

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引用次数: 1

Abstract

The rod-pinch diode [(R.A. Mahaffrey et al., 1978), (G. Cooperstein et al., 2001)] is a cylindrical, pinched-beam diode being developed as a radiography source [R.J. Commisso et al., 2002]. The diode consists of a small radius anode rod extending through the hole of an annular cathode. The diode has been operated at 1 to 5 MV with an impedance of 20 to 50 /spl Omega/, a FWHM pulse width of 20 to 50 ns, and an anode radius as small as 0.25 cm [(R.A. Mahaffrey et al., 1978), (G. Cooperstein et al., 2001), (R.J. Commisso et al., 2002)]. The diode is designed to run at critical current so that electrons emitted from the cathode flow axially along the anode rod and pinch radially onto the rod tip. Typically, ion emission from the anode is required for propagation of the pinch along the rod. Without ions, the pinch would occur on the anode rod just downstream of the cathode disk. In order to assure that a given diode will be properly designed to run at critical current requires a detailed knowledge of the diode impedance characteristics. Initially, a laminar flow model [B.V. Oliver et al., 2001] was developed to describe the rod-pinch diode. Although this model provides considerable insight into diode operation, PIC simulations show that the electron flow is not laminar [G. Cooperstein et al., 2001]. The model of [B.V. Oliver et al., 2001] was extended to include transverse electron pressure in order to consider the effects of nonlaminar flow [P.F. Ottinger et al., 2002]. However, a form for the transverse pressure tensor is required to close the equation set in this model and only special forms of the pressure tensor are analytically tractable. Here, a Vlasov model for the diode electron flow is developed using an electron distribution function with properties that are well characterized and directly related to a rod-pinch diode. In this model, the pressure tensor is self-consistently derived.

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棒箝位二极管阻抗的Vlasov模型

棒箝位二极管[a]Mahaffrey et al.， 1978)， (G. Cooperstein et al.， 2001)]是一种圆柱形的夹束二极管，正在开发作为射线照相源[R.J.Commisso et al.， 2002]。该二极管由一个小半径的阳极棒穿过环形阴极的孔延伸而成。二极管工作在1至5 MV，阻抗为20至50 /spl ω /， FWHM脉冲宽度为20至50 ns，阳极半径小至0.25 cm [(R.A.)Mahaffrey et al.， 1978)， (G. Cooperstein et .， 2001)， (R.J. Commisso et al.， 2002)]。二极管被设计成在临界电流下运行，这样从阴极发射的电子沿阳极棒轴向流动，并径向夹紧到阳极棒尖端。通常情况下，从阳极发射的离子是沿棒传播捏的必要条件。如果没有离子，这种挤压就会发生在正极盘下游的阳极棒上。为了确保给定的二极管将被适当地设计为在临界电流下运行，需要对二极管阻抗特性有详细的了解。最初，层流模型[B.V.Oliver等人，2001]是用来描述棒捏二极管的。尽管该模型对二极管的工作提供了相当深入的了解，但PIC模拟表明电子流不是层流的[G]。Cooperstein et al.， 2001]。[B.V.]的模型Oliver et al.， 2001]为了考虑非层流的影响，将横向电子压力纳入了研究范围Ottinger et al.， 2002]。然而，需要一种横向压力张量的形式来关闭该模型中的方程集，并且只有特殊形式的压力张量是可解析处理的。在这里，利用电子分布函数开发了二极管电子流的弗拉索夫模型，该模型具有很好的特征，并与棒捏二极管直接相关。在该模型中，压力张量是自洽导出的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Digest of Technical Papers. PPC-2003. 14th IEEE International Pulsed Power Conference (IEEE Cat. No.03CH37472)

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